This application proposes a comparative study of the adenosine deaminase binding proteins (complexing proteins) of human tissue. The complexing proteins of plasma and spleen (in the form of high molecular weight adenosine deaminase) will be isolated by procedures utilizing immunoadsorbant column chromatography. A similar procedure has been used successfully to provide purified kidney complexing protein for this study. The proposed comparison of the subunit structure, immunochemical properties and chemical composition should be helpful in determining if these proteins are products of the same gene. Other tissues will be surveyed by immuno-chemical techniques to identify sources of variant forms of complexing protein suitable for future investigation. An immunoassay for complexing protein will be developed and used to measure the levels of complexing protein in the serum of immunodeficient patients. It is hoped this study will lead to a better understanding of the in vivo function of adenosine deaminase and its relationship to the development of the immune response.